--- /dev/null
+/* mpn_popcount, mpn_hamdist -- mpn bit population count/hamming distance.
+
+Copyright 1994, 1996, 2000, 2001, 2002, 2005 Free Software Foundation, Inc.
+
+This file is part of the GNU MP Library.
+
+The GNU MP Library is free software; you can redistribute it and/or modify
+it under the terms of the GNU Lesser General Public License as published by
+the Free Software Foundation; either version 3 of the License, or (at your
+option) any later version.
+
+The GNU MP Library is distributed in the hope that it will be useful, but
+WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
+or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
+License for more details.
+
+You should have received a copy of the GNU Lesser General Public License
+along with the GNU MP Library. If not, see http://www.gnu.org/licenses/. */
+
+#include "gmp.h"
+#include "gmp-impl.h"
+
+#if OPERATION_popcount
+#define FNAME mpn_popcount
+#define POPHAM(u,v) u
+#endif
+
+#if OPERATION_hamdist
+#define FNAME mpn_hamdist
+#define POPHAM(u,v) u ^ v
+#endif
+
+unsigned long
+FNAME (mp_srcptr up,
+#if OPERATION_hamdist
+ mp_srcptr vp,
+#endif
+ mp_size_t n)
+{
+ unsigned long result = 0;
+ mp_limb_t p0, p1, p2, p3, x, p01, p23;
+ mp_size_t i;
+
+ ASSERT (n >= 1); /* Actually, this code handles any n, but some
+ assembly implementations do not. */
+
+ for (i = n >> 2; i != 0; i--)
+ {
+ p0 = POPHAM (up[0], vp[0]);
+ p0 -= (p0 >> 1) & MP_LIMB_T_MAX/3; /* 2 0-2 */
+ p0 = ((p0 >> 2) & MP_LIMB_T_MAX/5) + (p0 & MP_LIMB_T_MAX/5); /* 4 0-4 */
+
+ p1 = POPHAM (up[1], vp[1]);
+ p1 -= (p1 >> 1) & MP_LIMB_T_MAX/3; /* 2 0-2 */
+ p1 = ((p1 >> 2) & MP_LIMB_T_MAX/5) + (p1 & MP_LIMB_T_MAX/5); /* 4 0-4 */
+
+ p01 = p0 + p1; /* 8 0-8 */
+ p01 = ((p01 >> 4) & MP_LIMB_T_MAX/17) + (p01 & MP_LIMB_T_MAX/17); /* 8 0-16 */
+
+ p2 = POPHAM (up[2], vp[2]);
+ p2 -= (p2 >> 1) & MP_LIMB_T_MAX/3; /* 2 0-2 */
+ p2 = ((p2 >> 2) & MP_LIMB_T_MAX/5) + (p2 & MP_LIMB_T_MAX/5); /* 4 0-4 */
+
+ p3 = POPHAM (up[3], vp[3]);
+ p3 -= (p3 >> 1) & MP_LIMB_T_MAX/3; /* 2 0-2 */
+ p3 = ((p3 >> 2) & MP_LIMB_T_MAX/5) + (p3 & MP_LIMB_T_MAX/5); /* 4 0-4 */
+
+ p23 = p2 + p3; /* 8 0-8 */
+ p23 = ((p23 >> 4) & MP_LIMB_T_MAX/17) + (p23 & MP_LIMB_T_MAX/17); /* 8 0-16 */
+
+ x = p01 + p23; /* 8 0-32 */
+ x = (x >> 8) + x; /* 8 0-64 */
+ x = (x >> 16) + x; /* 8 0-128 */
+#if GMP_LIMB_BITS > 32
+ x = ((x >> 32) & 0xff) + (x & 0xff); /* 8 0-256 */
+ result += x;
+#else
+ result += x & 0xff;
+#endif
+ up += 4;
+#if OPERATION_hamdist
+ vp += 4;
+#endif
+ }
+
+ n &= 3;
+ if (n != 0)
+ {
+ x = 0;
+ do
+ {
+ p0 = POPHAM (up[0], vp[0]);
+ p0 -= (p0 >> 1) & MP_LIMB_T_MAX/3; /* 2 0-2 */
+ p0 = ((p0 >> 2) & MP_LIMB_T_MAX/5) + (p0 & MP_LIMB_T_MAX/5); /* 4 0-4 */
+ p0 = ((p0 >> 4) + p0) & MP_LIMB_T_MAX/17; /* 8 0-8 */
+
+ x += p0;
+ up += 1;
+#if OPERATION_hamdist
+ vp += 1;
+#endif
+ }
+ while (--n);
+
+ x = (x >> 8) + x;
+ x = (x >> 16) + x;
+#if GMP_LIMB_BITS > 32
+ x = (x >> 32) + x;
+#endif
+ result += x & 0xff;
+ }
+
+ return result;
+}